Hackaday Links: January 24, 2016

The RepRap wiki was spammed this week. Everything is fine now, but I feel I should call attention to the fact that the RepRap wiki needs some people to contribute, organize, and maintain everything. The wikis for obscure anime shows are better than the RepRap wiki, so if you’re looking to contribute to an important open source project, there ‘ya go.

The 200cc, 5.5HP, 4-stroke OHV Honda GX200 engine is found in a whole lot of tools, and is a fantastic power plant to build a go-kart around. It also costs about $350. There are clones of this engine available direct from China for about $100. Here’s how you add a turbo to one of these clone engines.

Freescale makes some pretty cool sensors and [Juan Ignacio Cerrudo] figured they needed breakout boards. He has some boards for a low-power three-axis accelerometer, an accelerometer and magnetometer, and a pressure sensor.

The Tektronix TDS744A is an older but still extremely capable 500MHz, 2Gsps, 4-channel scope. You can upgrade it to the 1GHz TDS784A by desoldering a few resistors. Very cool if you’re looking for a cheap-ish 1GHz scope.

[TheBackyardScientist] hung out with some cub scouts a few weekends ago and launched a high altitude balloon over Florida. The payload included a game camera, APRS tracker, GoPro, and a few other bits and bobs. The balloon reached 106,000 feet and landed only a few miles from Cape Canaveral.

Big RC planes – UAVs especially – are a pain to launch. Flying wings above a certain size are just dangerous to launch by hand, and landing gear is heavy and for the most part unnecessary. What’s the next best solution? A trebuchet, of course. It mounts on a car and is able to give a UAV a little bit of altitude and some speed. A pretty good idea that could be easily implemented with some load-bearing PVC pipe.

Everybody likes the Game of Life, so here’s one built with a 6502. It’s built around a Western Design Center 65c816 board we’ve seen before, nine MAX7219 LED controllers mapped to the VIA, and nine 8×8 LED matrix displays. Here’s a video of it in action.

About a month ago, a search of AliExpress turned up Apple’s A8 CPU. I bought one. Here’s what I got. It’s a stupidly small pitch BGA, and I don’t have a datasheet. What am I going to do with it? Make a non-functioning board with a few ports, resistors, no traces, and the A8 chip planted square in the middle.

Software Controlled Hard Drive Solenoid Engine

[Fabien-Chouteau] submitted his interesting solenoid engine. In an internal combustion, steam, or pneumatic piston engine, the motive force is produced by expanding gas. In [Fabien]’s little engine it is produced by the arm of a hard drive. Solenoid engines are usually just for show, and come in all shapes and sizes. If you want to move something using electricity an axial motor is probably a better bet. But if you want a challenge and a learning experience, this is hard to beat.

[Fabien] had some problems to solve before his motor made its first revolution. Just like a piston engine the timing needed to be exact. The arm firing at the wrong time could cause all sorts of trouble, the equivalent of backfire in a combustion engine. A STM32f4 discovery board was coupled with a Hall-effect sensor and a MOSFET. When the board read that the arm has moved back to the most efficient position for firing it sent a pulse through the coil. Just like a regular engine, getting the timing right makes all the difference. Once [Fabien] got it tuned up his motor could spin around at a steady 3000 rpm.

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Motorized Picnic Table Terrorizes Perth Streets

There is a public menace on the streets of Perth, Australia: two motorized picnic tables. Police are looking for the drivers of the, erm, vehicles, which were seen cruising down the West Coast Highway, complete with passenger casually sitting on the tables having a drink. It looks like the two picnic tables are being driven by a centrally mounted lawnmower motor and are controlled from one of the seats. The police are interested because it is illegal to drive something on the public road in Australia that isn’t properly licensed. I’ll bet that his insurance probably doesn’t cover taking it out for a spin on the highway, either. The accompanying TV news report does not identify the person responsible, but they claim have spoken to the builder, who says that the two tables can manage up to 50 miles per hour. They claim that he is even working on an upgraded model that includes a built-in barbecue, which could bring a whole new meaning to the term drive-thru.

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The Simplest Steam Engine

[RimstarOrg] has posted an awesome writeup on his Hero’s steam engine . Hero’s engine is a Greek design from the first century and is the earliest known steam engine. It’s amazing to think he developed the engine seventeen centuries before the industrial revolution, and yet it was largely ignored. While you can find more faithful replicas, of this landmark machine [RimstarOrg]’s rig can’t be beaten for simplicity and he does a great job of explaining the principal of operation and construction.

Using a soda can filled with water and a propane torch [RimstarOrg] was able to get the can to rotate rapidly by ejecting steam from two holes in the side of the can. A fishing swivel is used to provide a pivoting joint and allow the can to rotate freely.

While we’ve covered steam engines before, we loved this simple design, and can’t wait to see what [RimStarOrg] comes up with next.

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Hackaday Prize Entry: Open Source Diesel

There are plans for open hardware farming equipment that can be brought to third world countries to relieve the beasts of burden and increase the production of fields. Want an open source car? You can 3D print one. Just about anything you can strap a motor to has been replicated in open hardware; all you need to do is buy a motor and bolt it on.

But what about the motors themselves? For his entry to The Hackaday Prize, [Shane] is designing an open source engine. It’s small, it’s a two-stroke, and it’s diesel, but it’s completely open hardware; a great enabling project for all the open source dirt bikes and microcombines.

The design of [Shane]’s engine is based on the Junkers Jumo 205; a weird engine that had opposing pistons in one cylinder. This allows the engine to have variable compression, allowing for a wide variety of fuels to be used. If you have kerosene, that’ll work with this engine. French fry oil will as well. It’s exactly what you need for an engine that could be used for anything.


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Bisected Engine Makes Cute Lamp – Still Cranks

As a beginner’s step towards the famous Top Gear V8 coffee table, [English Tea] converted a small single cylinder engine into a desk lamp that uses the mechanical actuation of the piston to turn on and off. No able-bodied engines were harmed in the making of this hack as this one was already a corpse — perfect for [Mr. Tea] to prop up and display in his home.

Regrettably lacking a lightsaber, he settled for 30 minutes on a hacksaw to split the cylinder followed by some sandblasting to clean all the rust, paint, and gunk off all the internals. Once it was clean he repainted it himself. Between paint and clearcoats, he figured he added 20 layers onto the metal.

Next he created some wood sections and wet-formed leather over them which he later dyed black. Caring less about a new Walmart lamp than the motor, he vivisected it for its electrical components and wired it up.

Without a crank on the shaft it looks a bit awkward to twist the lamp on or off, but, only enough pressure is needed to poke a latching momentary pushbutton and it seems to work just fine. For any readers looking to make their own, dead compressors and gas power tools are fairly common and nearly free at the junkyard. Engine-based projects can be intimidating to start if you need a working engine again at the end. Becoming familiar with them on a project like this where you are mostly only using the engine as a building material is an easy way to get your foot in the door.

See the video after the break of the piston bumping the light on and off.

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The DIY Open Crank Engine Moped

Anyone can strap a two-stroke engine on a bicycle to create a moped. But [robinhooodvsyou] has created something infinitely more awesome. He’s built an inverted open crank engine on a 10 speed bicycle. (YouTube link)  As the name implies, the engine has no crankcase. The crankshaft, camshaft, and just about everything not in the combustion chamber hangs out in the open where it can be seen and appreciated.

[robinhooodvsyou] started with an air-cooled Volkswagen cylinder. He filled the jug with a piston from a diesel car. Camshaft, flywheel, valves, and magneto are courtesy of an old Briggs and Stratton engine. The cylinder head, crankshaft, pushrods, and the engine frame itself are all homemade.

Being an open crank engine, lubrication is an issue. The crankshaft’s ball bearing is lubricated by some thick oil in a gravity fed cup. Even though the engine is a four-stroke,[robinhooodvsyou] adds some oil to the gas to keep the rings happy. The camshaft and connecting rod use Babbit bearings. While they don’t have an automatic oiling system, they do look pretty well lubricated in the video.

Starting the engine is a breeze. [robinhooodvsyou] created a lever which holds the exhaust valve open. This acts as a compression release. He also has a lever which lifts the entire engine and friction drive off the rear wheel. All one has to do is pedal up to cruising speed, engage the friction drive, then disengage the compression release.

We seriously love this hack. Sure, it’s not a practical vehicle, but it works – and from the looks of the video, it works rather well. The unmuffled pops of that low 4:1 compression engine reminds us of old stationary engines. The only thing we can think to add to [robinhooodvsyou’s] creation is a good set of brakes!

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